1. Field of the Invention
The invention concerns an interior cooling body for a blown film system, a blown film system, and a process for producing a blown film.
2. The Prior Art
Blown film systems are used for producing large scale films in the form of tubes from thermoplastic synthetic material.
DE 1 211 379 shows a system wherein a tube is produced from an annular slit valve. The tube is widened by introducing blown air between the valve and a water-operated cooling body.
DT 26 08 311 A1 shows a system wherein the tube is cooled down at its interior side by a water-operated cooling body, whereas at its exterior side, the tube is in direct contact with the water. The exterior cooling water runs downwards along the tube. Thus, the system is used for plants extruding from top to bottom.
DE 39 03 174 A1 shows a blown film system with a cooling cylinder within the tube with four cooling air grooves running around the cooling cylinder at four discrete points of height.
DE 29 24 897 A1 shows a cylindrical stabilizer for a resin bubble which heats and widens the bubble from the interior side. On the outside, there is a cooling air fan. The interior stabilizer has concave and convex engraved and cut patterns, especially in the form of grooves.
DE 1 504 648 shows a system for cooling a film tube by blown air running along a water-operated interior cooling body with a sand-blasted surface.
Further systems are known from U.S. Pat. No. 3,650,644, AT 315 472, DE 26 39551 A1, and DE 38 15415 A1.